Dampening system for offset press



June 20, 1967 c, w M 3,326,122

DAMPENING SYSTEM FOR OFFSET PRESS Filed Jan. 18, 1965 INVENTOR. FREDRIC C. WILDEMAN W 7 ATTORNEYS Patented June 20, 1967 3,326,122 DAMPENING SYSTEM 1 R QFFSET PRESS Fredric C. Wildeman, 2515 Norwood Piace, Madison, Wis. 53795 Filed fan. 18, 1965, Ser. No. 426,073 9 Claims. (Cl. 101148) This invention relates to improvements in dampening methods and mechanisms and more particularly, dampening methods and mechanisms for offset printing presses.

Various types of dampening mechanisms have been used with offset printing presses for a number of years. However, prior to the present invention they have each been subject to one or more disadvantages.

One conventional dampening mechanism in widespread use at the present time employs a system of four revolving rollers in combination with a revolving plate cylinder which carries the printing plate. The first roller is independently driven, and normally revolves at a much slower speed than the three remaining rollers and the plate cylinder, which are normally in rolling contact and revolve at the speed of the printing press. The first roller or pan roller, is in contact with a supply of water or other suitable liquid. The second roller shifts out of contact with the third roller and into contact with the first roller every third or fourth revolution of the plate cylinder to thereby pick up liquid from the first roller. The amount of liquid which the second roller picks up may be regulated by the speed of revolution of the first roller and/or the contact dwell time between the first two rollers. The second roller then shifts back into rolling contact with the third roller, and transfers the liquid to the third roller, fourth roller and plate cylinder duringthe next three or four revolutions of the plate cylinder. The second roller then repeats the process to pick up more liquid for the plate cylinder during succeeding revolutions.

The primary disadvantage of this dampening mechanism is obvious. When the liquid first reaches the plate cylinder an excessive amount can be expected to be provided during the first revolution of the plate cylinder, approximately the right amount of liquid may be transferred during the sec-0nd revolution and less than the desired amount will be provided during the third revolution of the plate cylinder. In practice, in order to transfer enough liquid to the plate cylinder for the third revolution, it is normally necessary to transfer more than enough liquid on both the first and second revolutions.

As a result, the quality of the printing is not as good, nor as consistent, as it should be. In addition, such a mechanism requires a relatively complex cycling and shifting mechanism to shift the second roller back and forth as desired.

In such previous conventional systems, the dampening mechanisms for the lower plate cylinders of certain twocolor and perfecting presses have normally been identical to the dampening mechanism for the upper plate cylinder, except that the second, third, fourth and fifth roller rotate in the opposite direction. A major disadvantage of this mechanism is that when the first two rollers are brought into contact a spray of liquid is often ejected upwardly toward the paper or other printing medium traveling above the rollers, and adversely affects the quality of the printing. This has been a primary source of trouble with such mechanisms for years.

Another widely used dampening system employs a pan roller in sliding contact with an ink roller which is in rolling contact with the plate cylinder to thereby transfer ink thereto. The pan roller transfers dampening liquid to the ink roller, which in turn transfers the liquid, along with the ink, to the plate cylinder. The disadvantages of this system are its high initial cost, and the fact that in use it is normally necessary to employ a dampening liquid which includes about 25% alcohol to substantially prevent mixing of the dampening liquid and the ink on the ink roller and plate cylinder. The operating costs for such an alcohol solution during the life of the press are very substantial as compared to the low cost of water, which may be used in many other dampening systems.

Still other conventional dampening mechanisms are quite complex, expensive, difficult to install, and/or do not produce printing of the required quality.

Therefore, it is a primary object of the present invention to provide a dampening mechanism which is adapted to apply moisture to the plate cylinder of an offset printing press at a uniform rate.

It is a further object of the present invention to provide an improved dampening mechanism which is relatively inexpensive to install and economical to operate.

It is a still further object of the present invention to provide a versatile dampening mechanism which, with only slight modification, may be used with both the upper and lower plate cylinders of a Web-fed or sheet-fed offset printing press.

It is an additional object of the present invention to provide a dampening mechanism for use with an offset printing press which will provide a uniform high quality of printing.

It is another object of the present invention to provide an improved method of applying a uniform and continuous quantity of moisture to the rotatable plate cylinder of an offset printing press.

Other objects and advantages of this invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing wherein preferred embodiments of the principles of this invention have been selected for exemplification.

FIG. 1 schematically illustrates my invention in combination with the upper plate cylinder of an offset printing press.

FIG. 2 schematically illustrates my invention in combination with the lower plate cylinder of an offset printing press.

Referring more particularly to the drawings, FIG. 1 schematically illustrates my novel improved dampening mechanism 10 for transferring liquid to the surface of the rotatable upper plate cylinder 16 of an offset printing press. The upper plate cylinder 16 prints the upper surface of a sheet or web of material being fed through the press. My dampening mechanism 10 comprises a plurality of revolvable parallel rollers including a water fountain roller 11, a first transfer roller 12, an idler roller 13, an intermediate roller 14, and a form dampener roller 15. The first transfer roller 12, idler roller 13, intermediate roller 14, and form dampener roller 15 are in rolling contact, as shown, and may be generally designated as upper transfer rollers. The form dampener roller 15 is in rolling contact with the upper plate cylinder 16, such that the upper transfer rollers 12, 13, 14, and 15, together with the upper plate cylinder 16, operate at the speed of the press, a typical surface speed being 600 feet per minute. The plate cylinder 16 and the intermediate roller 14 are normally gear driven, and the intermediate roller is preferably adapted to oscillate back and forth along its longitudinal axis during rotation. The form dampener roller 15 is driven by the intermediate roller 14 and plate .cylinder 16 in contact therewith; the first transfer roller 12 is driven by the intermediate roller 14; and the idler roller is driven by the first transfer roller 12.

The water fountain roller 11 is independently driven at a much slOWer speed than the other rollers. The Water fountain roller 11, or pan roller as it is sometimes called, extends into the pan 17 located directly below the water fountain rollerll to a point below the level of the water 3 or other liquid in the pan 17. When the fountain rtller 11 revolves, it picks up liquid from the pan 17, the rate of liquid pick-up depending upon the speed at which the roller 11 is revolving.

In operation, the upper plate cylinder 16 and the rollers rotate in the directions indicated by the arrows in FIG. 1. The fountain roller 11 and the first transfer roller 12 are shown to be in closely spaced relation. In actual practic, such spacing 18 will be very slight, typically less than or equal to approximately 0.002 of an inch. Alternatively, the fountain roller 11 and first transfer roller 12 may be positioned in slight sliding contact despite the fact that their surfaces are moving in the same direction at the point of contact because of the difference in surface speeds of the two revolving rollers. When in such slightly spaced relation or sliding contact, the first transfer 12 will continuously pick up a film of liquid from the fountain roller 11, and such liquid is continuously transferred to the plate cylinder 16 by means of the contacting intermediate roller 14 and form dampener roller 15. The rate at which liquid is transferred to the plate cylinder 16 will depend upon the speed of the fountain roller 11.

Because of the difference in surface speeds of the fountain roller 11 and first transfer roller 12, a spray 18a of liquid will normally be ejected downwardly from the spacing 18, or point of contact, between the two rollers. This spray 18a is prevented from being lost or from striking and adversely affecting the material being printed by the presence of idler roller 13. The idler roller 13 is positioned in the path of the ejected spray 18a of liquid .to pick the ejected liquid up on its surface, and is in rolling contact with the first transfer roller 12 to transfer the picked up liquid back to the first transfer roller 12 for transfer to the plate cylinder 16, as described above. Thus, the ejected spray 18a is efficiently utilized by my dampening mechanism.

It is seen from the above discussion that my dampening mechanism may be operated to supply a continuous flow of liquid to the plate cylinder 16 at any desired rate. Consequently, utilization of my mechanism permits the operator to maintain exactly the amount of liquid desired on the plate cylinder 16 to insure consistent, high quality printing at all times. Further, since with my mechanism the liquid is transformed directly from the form roller to the plate cylinder 16, without intermediate transfer to the ink rollers (not shown) in rolling contact with the plate cylinder 16, it is not necessary to use alcohol in .the wetting medium for most printing operations. This results in a great saving in operating costs during the life of the press, as compared to some other dampening mechanisms which apply the dampening liquid to one of the ink rollers of the press and which must use an alcohol- Water solution as the wetting medium to prevent undezsirable mixing with the ink on the ink rollers. On the other hand, an alcohol-water solution may be employed with my mechanism, if desired, for certain printing jobs .in which it is difiicult to maintain the separation desired between the water and the ink, or to cause the wetting liquid to evaporate off the plate cylinder at a faster rate than will water alone.

FIG. 2 illustrates my novel dampening mechanism 20 for use with the lower plate cylinder 26 which prints the lower surface of a web or sheet of material (not shown) being fed through the offset printing press. As in previously described conventional dampening systems, the water fountain roller 21 for the lower plate cylinder 26 revolves in the same direction (clockwise) as the upper water fountain roller 11. The lower plate cylinder 26, form dampener roller and intermediate roller 24 revolve in directions opposite to those of their upper counterparts, also similar to previously described dampening systems. The lower first transfer roller 22 is caused to rotate in the same counterclockwise direction as the upper first transfer roller 12 by positioning the idler roller 23 in rolling contact with the independently driven intermediate roller 24 and placing the first transfer roller 22 in rolling contact with the idler roller 23. Thus, the lower first transfer roller 22 will be driven by the idler roller instead of the intermediate roller, as in the upper dampening mechanism 16'. The lower first transfer roller 22 will be located in the same slightly spaced or sliding relatron to the lower water fountain roller 21 as the upper first transfer roller 12 is located with respect to the upper fountain roller 11. Likewise, the idler roller 23 will be positioned as shown to pick up the spray 28a of liquid ejected from the space 28 betwen the fountain roller 21 and the first transfer roller 22, and transfer said ejected liq-uid back to the first transfer roller 22 and/ or the intermediate roller 24 for eventual transfer to the lower plate cylinder 26. Thus, it is seen that except for the fact that the direction of revolution of the lower plate cylinder 26, form dampener roller 25 and intermediate roller 24 has been reversed, the operation of my lower dampening mechanism 21? is exactly the same as the operation of my upper dampening mechanism 10. In particular, the relation of the fountain rollers 11 and 21, first transfer rollers 12 and 22 and idler rollers 13 and 23 are substantially the same in each mechanism, with the result that a desired amount of liquid is continuously transferred from the lower fountain roller 21 to the lower plate cylinder 26 by the lower transfer rollers 22, 23, 24 and 25.

The surfaces of the rollers of my mechanism should be adapted to readily accept water or some other desired dampening medium and repel grease to provide for efiicient transfer of the dampening medium to the plate cylinder. As in prior conventional systems, the fountain rollers 11 and 21 and the gear driven intermediate rollers 14 and 24 are preferably chrome plated, while the first transfer rollers 12 and 22, idler rollers 13 and 23, and form dampener rollers 15 and 25 preferably have resilient outer surfaces. Thus, the roller surfaces in rolling contact with the chrome plated roller surfaces are all comprised of a resilient material, which may "be in the form of dampening sleeves which are shrunk onto their respective rollers to provide the desired resilient surface. One suitable type of dampening sleeve is manufactured by the Minnesota Mining and Manufacturing Company of Saint Paul, Minn, under the trade name 3M Brand, and is constructed of plastic film material having a thickness of 0.006 inch or less. Another type of dampening sleeve which is particularly useful for use on the first transfer and idler rollers is constructed of textile material, examples of which are sold under the trade name Aquatex by the Godfrey Roller Company, and A-Tex by lomac, Inc. The form dampener rollers 15 and 25 may alternatively be wrapped with a conventional rag parchment type material manufactured under the name Plastodamp by the Ideal Roller Company. The first transfer rollers 12 and 22 may be in the form of rotary brushes to provide a still different type of resilient surface.

My improved dampening mechanisms 10 and 20 are less costly to install and maintain than prior conventional mechanisms or mechanisms employing ink rollers to apply the dampening liquid to the plate cylinder. Since the first transfer rollers 11 and 21 of my mechanisms remain stationary rather than shifting back and forth between the fountain roller and intermediate roller as in prior conventional mechanism, no complicated cycling and shifting mechanism is required. Further, such a conventional dampening system can be converted to the mechanism of my invention by simply adding the idler roller and positioning the rollers such that the first transfer roller is located in spaced or sliding relation to the fountain roller and in rolling contact with the intermediate roller for the upper dampening mechanism 10 or with the idler roller for the lower dampening mechanism 20. The idler roller 23 for the lower dampening mechanism 20 should also be located in rolling contact with the intermediate roller 24, as shown in FIG. 2. Finally, the first transfer rollers 12 and 22, idler rollers 13 and 23 and form dampener rollers and should preferably be fitted with dampener sleeves as described above. Such a conversion to my improved dampening mechanism will provide more uniform wetting at the rate desired, and at a minimal initial cost.

By operating independently of the press ink rollers, my mechanism also avoids the costly installation and operating expenses of dampening mechanisms employing the ink rollers to dampen the plate cylinder.

It is understood that the present invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as may come within the scope of the following claims:

I claim:

1. A dampening mechanism for an offset printing press having a revolvable plate cylinder, said mechanism comprising:

(a) a substantially cylindrical, revolvable fountain roller located in substantially parallel relation to said plate cylinder, said fountain roller being partially immersed in a quantity of liquid to be transferred to the surface of said plate cylinder,

(b) a plurality of substantially cylindrical, revolvable transfer rollers being interposed between said fountain roller and said plate cylinder in substantially parallel, successive rolling contact,

(c) one of said transfer rollers being positioned parallel to said fountain roller such that its surface is located in close proximity to the parallel surface of and fountain roller and said proximate surfaces will travel in the same direction during revolution of said rollers whereby liquid will be continuously transferred from said fountain roller thereto when said fountain roller and said one transfer roller are revolving,

((1) another of said transfer rollers being parallel to and in further rolling contact with said plate cylinder such that liquid transferred from said fountain roller to said one transfer roller will be further transferred to said other transfer roller and said plate cylinder as said transfer rollers and said plate cylinder revolve, and

(e) said transfer rollers include an idler roller in rolling contact with said one transfer roller, said idler roller being positioned in such relation to said fountain roller and said one transfer roller that any liquid which may be ejected from between said fountain roller and said one transfer roller will be picked up by the surface of said idler roller and transferred to said plate cylinder by said transfer rollers.

2. The invention described in claim 1 wherein the proximate surfaces of the fountain roller and the one transfer roller are in sliding contact during revolution of said rollers, the surface of said one transfer roller moving at a much higher rate of speed than the surface of said fountain roller at the point of contact.

3. The invention described in claim 1 wherein the transfer rollers includes an intermediate roller, said intermediate roller being positioned in rolling contact with the other transfer roller which contacts the plate cylinder.

4. The invention described in claim 3 wherein the intermediate roller is gear driven and is adapted to oscil late back and forth along its longitudinal axis.

5. The invention described in claim 3 wherein the surfaces of the fountain roller and the intermediate roller are chrome plated, and wherein the surfaces of the one transfer roller, the idler roller and the other transfer roller are resilient.

6. The invention described in claim 3 wherein the intermediate roller is also in rolling contact with the one transfer roller in close proximity to the fountain roller.

7. The invention described in claim 3 wherein the intermediate roller is also in rolling contact with the idler roller.

8. A method of transferring and applying dampening liquid to the surface of a revolving plate cylinder for an offset printing press which comprises:

(a) maintaining a film of dampening liquid on a first moving surface parallel to the surface of said plate cylinder,

(b) continuously transferring liquid from said film on said first moving surface to a first cylindrical transfer surface by positioning said first transfer surface parallel to and in close proximity to said first moving surface and revolving said first cylindrical transfer surface at a greater surface speed than the speed of said first moving surface,

(0) continuously transferring said liquid from said revolving cylindrical surface to the surface of said revolving plate cylinder by interposing at least one additional cylindrical transfer surface therebetween in successive rolling contact with said first transfer surface and the surface of said revolving plate cylinder, and

(d) preventing loss of liquid from said first moving surface and said first transfer surface by positioning a second cylindrical transfer surface in rolling contact with said first transfer surface and in such relation to said proximate first moving surface and first transfer surface that liquid ejected from between.

said proximate surfaces is picked up by said second transfer surface and transferred to said plate cylinder by said transfer surfaces. 9. The method described in claim 8 wherein the first moving surface and the first transfer surface are positioned in sliding contact.

References Cited UNITED STATES PATENTS 1,419,189 6/19-22 Wood 101350 2,430,965 11/1947 Taylor 101350 2,435,452 2/1948 Linn et al 101-350 2,613,600 10/1952 McWhorther 101--350 2,842,053 7/1958 DeMarchi 101-349 3,106,154 10/1963 Saul 101148 3,168,037 2/1965 Dahlgren 101-l48 OTHER REFERENCES Inland Printer/Americal Lithographer, Whats New in Offset Dampening Systems, 2-1964, p. 58, 59, and 104, H. W. Gegenheimer.

ROBERT E. PULFREY, Primary Examiner.

H. P. EWELL, Assistant Examiner. 

1. A DAMPENING MECHANISM FOR AN OFFSET PRINTING PRESS HAVING A REVOLVABLE PLATE CYLINDER, SAID MECHANISM COMPRISING: (A) A SUBSTANTIALLY CYLINDRICAL, REVOLVABLE FOUNTAIN ROLLER LOCATED IN SUBSTANTIALLY PARALLEL RELATION TO SAID PLATE CYLINDER, SAID FOUNTAIN ROLLER BEING PARTIALLY IMMERSED IN A QUANTITY OF LIQUID TO BE TRANSFERRED TO THE SURFACE OF SAID PLATE CYLINDER, (B) A PLURALITY OF SUBSTANTIALLY CYLINDRICAL, REVOLVABLE TRANSFER ROLLERS BEING INTERPOSED BETWEEN SAID FOUNTAIN ROLLER AND SAID PLATE CYLINDER IN SUBSTANTIALLY PARALLEL, SUCCESSIVE ROLLING CONTACT, (C) ONE OF SAID TRANSFER ROLLERS BEING POSITIONED PARALLEL TO SAID FOUNTAIN ROLLER SUCH THAT ITS SURFACE IS LOCATED IN CLOSE PROXIMITY TO THE PARALLEL SURFACE OF AND FOUNTAIN ROLLER AND SAID PROXIMATE SURFACES WILL TRAVEL IN THE SAME DIRECTION DURING REVOLUTION OF SAID ROLLERS WHEREBY LIQUID WILL BE CONTINUOUSLY TRANSFERRED FROM SAID FOUNTAIN ROLLER THERETO WHEN SAID FOUNTAIN ROLLER AND SAID ONE TRANSFER ROLLER ARE REVOLVING, (D) ANOTHER OF SAID TRANSFER ROLLERS BEING PARALLEL TO AND IN FURTHER ROLLING CONTACT WITH SAID PLATE CYLINDER SUCH THAT LIQUID TRANSFERRED FROM SAID FOUNTAIN ROLLER TO SAID ONE TRANSFER ROLLER WILL BE FURTHER TRANSFERRED TO SAID OTHER TRANSFER ROLLER AND SAID PLATE CYLINDER AS SAID TRANSFER ROLLERS AND SAID PLATE CYLINDER REVOLVE, AND (E) SAID TRANSFER ROLLERS INCLUDE AN IDLER ROLLER IN ROLLING CONTACT WITH SAID ONE TRANSFER ROLLER, SAID IDLER ROLLER BEING POSITIONED IN SUCH RELATION TO SAID FOUNTAIN ROLLER AND SAID ONE TRANSFER ROLLER THAT ANY LIQUID WHICH MAY BE EJECTED FROM BETWEEN SAID FOUNTAIN ROLLER AND SAID ONE TRANSFER ROLLER WILL BE PICKED UP BY THE SURFACE OF SAID IDLER ROLLER AND TRANSFERRED TO SAID PLATE CYLINDER BY SAID TRANSFER ROLLERS. 